Turbo-fan rotor



Dec. 25, 1962 H. J. KENT 3,070,284

TURBO-FAN ROTOR Filed Oct. 7, 1960 2 Sheets-Sheet 1 INVENTOR.

x/zzeer .1 Kf/VT fivm p Dec. 25. 1962 H. J. KENT TURBO-FAN ROTOR 2 Sheets-Sheet 2 Filed Oct. 7, 1960 xii w INVENTOR. away .1 zz/vr BY 776 mm United States Patent htice 3,670,284 TURBGFAN RGTGR Harry J. Kent, Lebanon, Uhio, assignor to General Electric Company, a corporation of New York Filed Get. 7, 1%0, Ser. No. 61,248 6 Elairns. (til. 230-116) This invention relates to a tip bucket turbo-fan rotor construction, also called tip turbine, providing torsional strength and rigidity together with effective sealing between hot turbine gases and cold fan air. The turbo-fan of this invention has particular application in producing lift for a vertical take-oft aircraft.

Turbo-fan rotors having tip buckets may be described as rotor fans having a plurality of radial blades for producing a flow of air, and being driven by the flow of propelling gases directed against buckets carried at the blade tips or about the peripheral circumference described by the blade tips. The propelling gases are generated by suitable means, such as a gas turbine 'jet engine, and will therefore be at high temperature relative to ambient air.

In the construction described, the problem arises of insulating the outer periphery of the rotor, which carries the turbine buckets subjected to the high temperature propelling gases, from the inner portion of the rotor through which passes the air being driven by the fan. Due to the high temperature of the outer bucket portion of the rotor relative to the inner fan portion, a further problem arises in the necessity for thermal compensation of the means supporting the buckets and subjected to the hot blast of the propelling gases. Finally, whatever construction is provided to aflord the necessary heat insulation and the compensation, the rotor must retain the strength and rigidity to withstand great torsional, tangential and vibratory stresses inherent in the operation of a turbo-fan subjected to large loads.

The object of this invention is to provide an improved turbo-fan rotor.

Another object is to provide a turbo-fan rotor of the tip bucket type in which the fan blades and fan duct are insulated from the propelling gases directed about the peripheral tip buckets.

Another object is to provide a turbo-fan rotor of the tip bucket type having optimum strength and rigidity.

Briefly, and in accordance with one aspect of the invention, the turbo-tan rotor comprises a hub having mounted radially thereon a plurality of fan blades of suitable pitch so that, when rotated, an axial How of air is generated. A plurality of arcuate segments are joined together to form a ring, which is fixed about the peripheral circumference described by the fan blade tips. Each of these segments carries a plurality of turbine buckets fixed radially to the convex side of the arcuate segments. These carrier segments are of U-shaped cross-section with the parallel walls of the U extending toward the rotor hub. A plurality of cover members are bolted over the open side of the U. Alternate ones of these cover members are positioned across the spaces between adjacent ones of the bucket carrier segments, thus joining the segments into a continuous ring. Two annular bands, one on each axial side, are bolted to the ring of bucket carrier segments. The widths of these bands extend axially on each side of the bucket carrier ring, one on the upstream side of the fan annulus and one on the downstream side. These bends form a smooth, continuous, annular face, together with the cover members of the segmented carrier ring, thereby presenting a clean duct surface for the passage of air through the fan, while simultaneously providing an annular wall or seal separating the outer peripheral area of the turbine buckets from the inner area of 'the fan duct. in addition, the sealing hands, together with the cover members, join Patented Dec. 25, 1962 ii the bucket carrier segments into a continuous ring of great strength and rigidity. Proper alignment of the segments is thereby maintained in spite of the torsional stresses caused by the propelling gases impinging upon the pitch of the turbine buckets.

Further objects, features, and attending advantages of the invention will become apparent by reference to the following specifications and drawings, in which:

FIGURE 1 is a partial plan view of the turbo-fan rotor of this invention.

FIGURE 2 is a partial View in perspective of the segmental bucket carricrs and cover members joined thereto.

FZGURE 3 is a partial view in perspective of the sealing bands in an exploded relationship with respect to the segmental bucket carriers.

FIGURE 4 is a cross-sectional view of the outer peripheral portion of the turbo-fan rotor, showing the adjacent portion ofthe fan duct within which the fan buckets rotate.

Referring to FIGURE 1, a hub lti is fixed radially thereto a plurality of fan blades 11. A plurality of arcuate segments 12 have radially fixed thereto a plurality of turbine vanes or buckets 13. Turbine buckets 13 may be ioined about their outer periphery by a connecting band or shroud 14. The segmental bucket carriers 12 are of U-shaped cross-section, as may be seen from FIG- URES 2-4. These U-shaped carriers have integral side wall portions 15, which extend toward the hub ll) of the rotor. Fan blades 11 are joined to the concave side of segmental bucket carriers 12. as at 16 in FIGURE 4. Bridging the ends or rims of parallel wall portions 15 are a plurality of cover members, such as shown at 17 and 18. As best seen in FIGURE 2, the cover members 17 and 18 close the open end of the U-shaped channel formed by bucket carriers 12. Cover members 17 and 18 may be fixed across wall portions 15 by any suitable means, but in the preferred embodiment, which may be understood by reference to FIGURE 2, cover members 17 are provided with parallel upstanding tabs 19 which extend within the parallel wall portions 15 of bucket carriers 12. Tabs 19 are joined to wall portions 15 by suitable means, such as bolts or rivets, which pass through mating holes 2t? in the parallel wall portions 15 with the fastening arrangement in tabs 19 preferably allowing a loose pinned joint by enlarging holes 29. it will be understood by reference to FIGURES 1 and 2 that the cover members 17 join adjacent bucket carrier members 12. Each pair of bolt holes in a tab 19 of a cover member 17 mates with two holes, one in each end portion of adjacent ones of bucket carriers 12. It will be seen by reference to FIGURE 1 that two fan blades 11 terminate in each segmental bucket carrier 12, so that additional cover members 18 must be provided to cover the space between adjacent fan blades not covered by members 17. As seen in FIGURE 2, cover members 18 have parallel upstanding tabs 21, similar to tabs 19 of cover members 17. Tabs 21, however, need to be provided with only one bolt to a side, and suitable bolt holes 22 provided in the tabsll mate with similar holes 2b in the parallel wall portions 15 of bucket carriers 12 to provide a tight pinned joint. As will be understood by reference to FIGURE 1, the fan blades 11 will be fixed to bucket carriers 12 at a diagonal angle with respect to the parallel wall portions 15, due to the inherent pitch of the fan blades. For this reason, the adjacent end portions 23 of respective bucket carriers 12, are slanted at an angle substantially conforming with the pitch of fan blades 11, and, as shown in FIGURE 2, tabs 19 and 21 of cover members 17 and 13, respectively, are otlset from one another by a corresponding angle. It should be pointed out that each of the bolt holes '29, 22 of the cover members have fixed thereto on the interior side walls of the bands 26 are shown, each positioned on opposite axial sides of the ring formed by bucket carriers 12 and cover members 17 and 18 and coextensive therewith. Along the side of the bands adjacent the parallel side walls 15 of the bucket carriers there are provided a plurality of spaced upstanding tabs 27. With the bands 26 in their assembled position, the tabs 27 extend within the parallel side walls 15 of bucket carriers 12, as shown in FIGURE It will further be understood by reference to FIGURE 4 that the tabs 27 of bands 26, in their assembled position are in abutting relation with tabs 19 and tabs 21, respectively, of the cover members 17 and 13, and that the tabs of the bands and cover members, in turn, are in abutting relation with the parallel side walls 15 of the bucket carriers 12, the whole being joined together by the bolt or similar fastening means described above.

The rim 23 of each band 26 opposite to that rim carrying the tabs 27 is formed at right angles to the plane of the band so as to extend parallel to the tabs 27, best shown in FIGURE 3.

Referring again to FIGURE 4, reference numeral 29 generally designates the area within which turbine buckets l3 revolve, and may be defined by any wall portion 39 extending parallel to and on either side of the buckets 13. It is through this turbine bucket area 29 that the propelling gases are directed, flowing from nozzles or similar outlet means in one side wall 3% to the other, impinging upon the buckets 13 in transit. Reference numeral 31 generally designates the fan blade area, which is separated from the turbine bucket area by the bands 25 and cover members 17, 18. Shown in section in FIGURE 4 are a pair of annular seals 32, which may be fixed to wall portions 3% of the turbine bucket area, and which, as in the preferred embodiment, may be of the honeycomb type. The right-tangle portions 28 of bands 26 extend toward the honeycomb to form first and sec ond seals 32, and are slightly spaced from them.

The parallel wall portions 15 of bucket carriers 12 may, under conditions of extreme stress, lack rigidity due to their cantilever mounting upon the central base member which mounts the buckets. In order to stiffen and reinforce the extremities of the wall portions 15, a solid truss portion 33, shown in FIGURE 3, is provided along the outside edge of each wall portion. As illustrated, the truss makes use of the inherent strength of the triangle, thereby providing longitudinal and lateral rigidity to both wall portions 15.

In operation, as the hot propelling gases are directed against the peripheral tip rotor buckets 13, the segmental bucket carriers 12 are subjected to the elevated temperature. The segmented construction of the bucket carrier ring permits tangential expansion of the individual segments, and thus, natural dimensional growth without radial growth except for that inherent in the turbine buckets. The high pressure thrust of the propelling gases against the turbine buckets, and the pitch at which the buckets are set, results in axial stresses tending to twist or dislocate the segments of the bucket carrier ring into misalignment with one another. Counteracting these forces and holding the segments in precise alignment are the cover members 17 joining adjacent ones of the tandem sections, together with the rigid bands 26 bolted on eithert side of the carrier ring. At the same time that cover members 17 and bands 26 furnish rigidity and stability to the segmental bucket carrier ring and consequent lignment of the tangential forces driving the rotor, the same members, together with cover members 18 furnish a smooth duct face axially of the fan for the clean and uninterrupted passage of the air fiow therethrough. In addition, the same members and, in particular, the bands 26, provide insulation and sealing between the hot turbine bucket area about the outer rotor periphery, and the inner fan area through which the cooler air passes.

It is apparent by the preceding specification that the invention described will provide a turbo-fan rotor using tip turbine buckets in which is provided (I) strength and rigidity necessary to high performance, (2) effective sealing of the hot propelling gases which are thereby prevented from adversely affecting the inner parts of the fan or the air flow therethrough, and (3) a smooth and unobstructed duct through which the fan air may pass.

Although the foregoing embodiment has been illustrated and described, it is apparent that other changes and modifications may be made in the construction and arrangement of the various parts without departing from the scope of this invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

l. A turbo-fan rotor comprising a hub, a plurality of inner fan blades radially positioned on said hub, a plurality of arcuate segmental U-shaped bucket carrier members with the U opening inward, a plurality of tarbine bucket members radially positioned on the outer convex surface of each of said U-shaped carriers, segmental means joining said carrier members together to form a ring, and means forming a connection between the concave surface of said ring and the outer ends of said fan blades.

2. The invention of claim 1 having sealing means coextensive with and carried by said U-shaped members and extending axially on each side thereof.

3. A turbo-fan rotor comprising a hub, a plurality of inner fan blades radially positioned on said hub, a plurality of arcuate segmental bucket carriers of U-shaped cross-section having parallel wall portions on the side corresponding to their concave surfaces, a plurality of turbine bucket members radially positioned on the convex surfaces of said bucket carriers, a plurality of cover members arranged in tandem and fixed to said bucket carriers to close the open side of said U-shaped cross-section, alternate ones of said cover members joining adjacent ones of said bucket carriers together to form a ring, and means forming a connection between the concave surface of said ring and the outer ends of said fan blades.

4. The invention of claim 3 in which the longitudinal free edges of said parallel wall portions of said segmental bucket carriers include a plurality of tandem trusses of triangular cross-section.

5. A turbo-fan rotor comprising a hub, a plurality of inner fan blades radially positioned on said hub, a plurality of arcuate segmental bucket carriers of U-shaped cross-section having parallel wall portions on the side corresponding to their concave surfaces, a plurality of turbine bucket members radially positioned on the conyex surfaces of said bucket carriers to be subjected to propelling gases, a plurality of cover members arranged in tandem and fixed to said bucket carriers to close the open side of said U-shaped cross-section, alternate ones of said cover members joining adjacent ones of said bucket carriers together to form a ring, means forming a connection between the concave surface of said ring and the outer ends of said fan blades, gas sealing means between said turbine bucket members and said inner fan blades, said sealing means including in addition to said tandem cover members a first sealing ring disposed on one axial side of and flush with said tandem cover members and a second sealing ring disposed on the other axial side of and flush with said tandem cover members, said first and second sealing rings having tab portions abutting said wall portions of said bucket carriers, and said means to fix said cover members to said carriers also joining said sealing rings to said carriers to form a unitary structure.

6. The invention of claim 5 in which the longitudinal free edges of said parallel wall portions of said segmental 5 6 bucket carriers include a plurality of tandem trusses of 2,518,669 Browne Aug. 15, 1950 triangular cross-section. 2,625,365 Moore Jan. 13, 1953 2,819,870 Wayne Jan. 14, 1958 References Cited in the file of this patent 2,868,439 Hampshire et a1 Jan. 13, 1959' UNITED STATES PATENTS 5 FOREIGN PATENTS 2,398,140 Heppner Apr. 9, 1946 2,429,681 Griffith Oct. 28, 1947 584,125 Canada Sept- 1959 

